Researchers detected tire-associated chemicals — the antioxidant 6PPD and its toxic byproduct 6PPD-quinone — in roughly 60–100% of 150 urine samples collected from adults, children and pregnant women in South China. The compounds are known to harm aquatic species, but their effects on human health remain uncertain. NOAA has developed a test to track 6PPD-quinone in marine life, and scientists are urging that tire wear particles be classified as a distinct pollution category to guide monitoring and mitigation.
Tire Chemicals Found in Human Urine: Researchers Urge a New Pollution Category
Scientists warn that chemicals linked to tire wear are showing up inside people — and they say we may need to rethink how we classify and manage this type of pollution.
In a study published in Environmental Science & Technology Letters, researchers at the Guangdong Key Laboratory of Environmental Pollution and Health analyzed microscopic particles produced by vehicle tires and the chemicals those particles can release over time. The team collected 150 urine samples from three groups across South China — adults, children and pregnant women — to check for traces of tire-related compounds.
The investigators detected the tire antioxidant 6PPD and its oxidized breakdown product, 6PPD-quinone, in approximately 60–100% of the samples tested. While 6PPD is widely used in tires to prevent rubber degradation, its oxidation product 6PPD-quinone has been shown to be highly toxic to some aquatic species. The study's authors stressed that, although these chemicals are known environmental contaminants, there is limited research on whether and how they accumulate in humans and what health effects they might cause.
Why this matters: 6PPD is an antiozonant added to tires; when tire wear particles enter stormwater and roadside runoff they can oxidize to form 6PPD-quinone. That compound has been implicated in lethal effects on fish, raising concerns about potential risks to people through environmental exposure, food webs, or contaminated water.
NOAA Fisheries has developed an assay to detect 6PPD-quinone in fish, shellfish and marine mammals to help track how the chemical moves through food webs and accumulates in organisms. Researchers say such monitoring tools could support better ecological risk assessments and inform improvements to stormwater management systems.
Separately, a paper in Environmental Research identified tire wear particles as a leading source of microplastic pollution. These tiny fragments are derived from fossil-fuel–based materials and the complex mix of synthetic and natural rubbers plus hundreds of chemical additives used in tires. Some studies have linked microplastic exposure to elevated risks of cardiovascular disease, cancer and neurological disorders, though causal links to humans remain under investigation.
"We urgently need to classify tire particles as a unique pollution category," wrote Henry Obanya, a researcher at the University of Portsmouth, noting that the chemical complexity of tire wear makes its full impacts difficult to predict.
The authors and external experts call for expanded human biomonitoring, targeted toxicology studies, and practical mitigation: improved stormwater capture and treatment, reduced tire wear through road and tire design, and broader inclusion of tire wear in microplastic and chemical-pollution policies. For now, the findings add to mounting evidence that roadside pollution can affect both ecosystems and people, and they highlight the need for faster research and regulatory attention.
